Association between cardiac troponin testing at scheduled admission and mortality in patients with comorbidities

Background Cardiac troponin I (cTnI) is a gold-standard biomarker for detecting myocardial infarction. Recently, the prognostic role of cTnI was reported for stable coronary artery disease and other chronic diseases. This study aimed to evaluate the usefulness of cTnI testing at scheduled admission of patients with comorbidities. Methods We retrospectively enrolled patients with comorbidities who were admitted through the outpatient clinic from April 2010 to December 2018. The enrolled patients were divided into two groups depending on whether cTnI was measured at admission. The primary endpoint was the mortality rate at one year after admission. Secondary endpoints included 30-day and in-hospital mortality rates. Results A population of 50,119 patients was divided into two groups, with 43,974 (87.8%) patients included in the no cTnI group and 6,145 (12.2%) patients included in the cTnI group. The multivariable analysis showed a reduction of mortality at one year in the cTnI group [5.9% vs. 3.8%, hazard ratio (HR) =0.78; 95% confidence interval (CI): 0.68–0.89; P<0.001]. Among 5,882 propensity score-matched pairs, this trend persisted, and the mortality rate was significantly lower in the cTnI group (5.3% vs. 3.9%, HR =0.77; 95% CI: 0.65–0.91; P=0.002). Patients with cTnI measurements taken at admission underwent cardiac evaluation and therapy more frequently. Conclusions The measurement of cTnI at scheduled admission may affect the mortality during one year of follow-up. Further studies are needed to validate our results.